#include <iostream>
#include <iomanip>
#include <cmath>

using namespace std;

int main() {
    int n, m;

    while (cin >> n >> m) {
        if (m <= 0) {
            cout << 0 << endl;
            continue;
        }
        double tmp = n;
        double sum = n;
        for (int i = 1; i < m; ++i) {
            tmp = sqrt(tmp);
            sum += tmp;
        }
        cout << fixed << setprecision(2) << sum << endl;
    }

    return 0;
}
